This application is based on and claims priority to Japanese Patent Application No. 2001-184909, filed Jun. 19, 2001, the entire contents of which is hereby
1. Field of the Invention
The present invention relates generally to a tilt support mechanism for an outboard motor, and more particularly to an improved tilt support mechanism to hold a drive unit of an outboard motor at any position higher than a fully tilt down position.
2. Description of Related Art
An outboard motor typically has a bracket assembly to support its drive unit on an associated watercraft. The bracket assembly comprises a clamping bracket formed by a pair of bracket arms that are spaced apart from each other and a swivel bracket interposed between the bracket arms. The swivel bracket supports the drive unit for pivotal movement about a generally vertically extending steering axis. The bracket arms are mounted on a transom of the watercraft. A generally horizontally extending pivot pin forms a hinge coupling between the swivel bracket and the clamping bracket such that clamping bracket supports the swivel bracket for pivotal movement about a tilt axis of the pivot pin. Thus, the swivel bracket together with the drive unit can pivotally move between a fully tilted down position and a fully tilted up position.
Normally, the drive unit in the fully tilted down position can place a propulsion device, such as, for example, a propeller, in a submerged position with the watercraft resting on the surface of a body of water. In the fully tilted up position the orientation of the drive unit places the propulsion device above the body of water when the watercraft is moored. The drive unit can take any position between the fully tilted down position and the fully tilted up position, either to adjust the trim angle of the watercraft or to slightly raise the propulsion device when the watercraft travels through shallow waters.
A tilt support mechanism can be provided to support the swivel bracket and the drive unit at a desired tilt position. In order to form the tilt support mechanism, the clamping bracket defines a plurality of pairs of openings in the bracket arms and a tilt pin transversely extends through one of pairs of the openings. The tilt pin sets the lowermost position of the swivel bracket when the swivel bracket rests against the tilt pin.
For example, FIG. 1 illustrates an arrangement of the tilt support mechanism 10. The bracket arms 12 include five pairs of openings 14 and a tilt pin 16 extends transversely through one of the pairs of the openings 14. In the illustrated case, the tilt pin 16 extends through the pair of openings positioned second from the bottom. The swivel bracket 18 rests on the tilt pin 16. Each hole 14 of a pair of openings is directly aligned with the corresponding hole 14 in the other bracket arm 12.
In this arrangement, however, the bracket arms 12 include rear ends 20 that protrude toward a drive unit 22 in order to accommodate the array of openings 14. This protrusion necessarily limits an angle range for steering the drive unit. This problem becomes exacerbated with drive units having larger girths. For instance, outboard motors provided with a four-cycle engine often have a large volume lubricant reservoir disposed in the drive unit 22. The drive unit 22 consequently has a larger girth which limits the range of angular steering movement when used with the prior bracket assembly. In such case, the resulting interference between the rear ends 20 of the bracket arms 12 and the larger girth drive unit 22 limit the angular steering range of the outboard motor.
One aspect of the present invention involves a tilt support mechanism for an outboard motor that allows an associated drive unit of the outboard motor, which has a relatively large girth, to pivot through a large steering angle. The tilt support mechanism can also be used with smaller girth drive units to enhance further the range of steering movement of the outboard motor.
In accordance with one aspect of the present invention, an outboard motor comprises a drive unit and a bracket assembly adapted to be mounted on an associated watercraft. The bracket assembly comprises a swivel bracket arranged to support the drive unit for pivotal movement about a steering axis. A clamping bracket is arranged to support the swivel bracket for pivotal movement about a generally tilt axis that extends generally normal to the steering axis. The clamping bracket comprises a pair of bracket arms spaced apart from each other so that at least a portion of the swivel bracket can fit between the bracket arms. Each bracket arm defines a plurality of openings that are arranged next to one another along an arcuate line. The openings of one bracket arm generally align with the openings of the other bracket arm to form opposing pairs of openings. A tilt pin extends transversely through one of the opposing pairs of openings and is capable of being selectively removed therefrom and inserted into another opposing pair of openings. The tilt pin is arranged to limit movement of the swivel bracket between the bracket arms.
Another aspect of the present invention involves an outboard motor comprising a drive unit and a bracket assembly adapted to be mounted on an associated watercraft. The bracket assembly comprises a swivel bracket arranged to support the drive unit for pivotal movement about a steering axis. A clamping bracket arranged to support the swivel bracket for pivotal movement about a tilt axis that extends generally normal to the steering axis. The clamping bracket comprises a pair of bracket arms spaced apart from each other so that at least a portion of the swivel bracket can fit between the bracket arms. Each bracket arm defines a plurality of pin openings. A tilt pin is sized to fit within the pin openings on each bracket arm. All of the pin openings on each bracket arm are arranged in a single line next to one another and at least one of the pin openings on each bracket arm being positioned farther forward and higher than an adjacent pin opening.
Further aspects, features and advantages of the invention will become apparent from the detailed description of the preferred embodiment which follows.